Not to be a concern troll but... One minor concern I have with the "purchase" options you just described, Jim is this...
We're adding:
4. Purchase of MP3 (when available)
5. Purchase of MusicGiants lossless tracks (WMA, some are DRM protected, some are not)
We may add:
8. Purchase of track from CD Baby.
I'm afraid that all these options add too much complexity. That is, at heart, the beauty of the Amazon MP3 Store (and the iTunes store to a lesser degree, though differently focused).
Right there, you're listing four different possibilities for playability that the user is going to have to investigate and consider before buying. For a $0.99 "spur of the moment" purchase, that is way too much thinking and the user might just as often decide to forget it.
The beauty of the Amazon MP3 Store is that I know without thinking that every single track listed is in the same exact format and has the same exact usability. They'll all work on my iPod, they'll all work on my Sansa, and they'll all work with MC. The iTunes Store doesn't have quite the same uniformity, but every single track is guaranteed to work with iTunes and with your iPod, so you don't need to care. Plus, they have very rigid price uniformity.
With this store... Even if they're all very clearly marked, most consumers don't know what the differences are at all. My mom doesn't care about Lossless vs. Lossy vs. DRM vs. DRM-free, and more importantly
doesn't care to learn. She just wants to buy a song and have it work on her iPod and on her computer without thinking about it. If she has to think about it, for a $0.99 "splurge" purchase, then you've already lost the sale.
Right now, your customers are going to have to choose between four differing options (not even counting the subscription model), and it sounds like availability is going to vary widely (some will only be available one way, some another, etc, etc). Fine for savvy consumers, but that is seriously limiting your customer base. The first time someone accidentally buys a Lossless WM DRM track and discovers that it won't work on their iPod (or heck, their Zune), they're going to be ticked off and probably never buy another track again.